Enamel deposition by electrophoresis is an application of the principle of using an electric current to convey particles of enamel in an enamel slip (e.g. in suspension in water) from a cathode to the surface to be convered which acts as an anode. Particles are conveyed preferentially along the lines of an electric field. When these lines are not very dense, as in the case of internal angles of the hollow body, it is necessary to place the cathode as near as possible to the centre of the radius of curvature of the angle.
The disadvantage of known methods is that the interior corners of hollow sheet metal parts are not coated with a layer of enamel which is thick enough to protect the sheet metal base, especially as chemical attacks tend to occur at these points.
Preferred application of the invention remedies this disadvantage by applying a sufficient thickness of enamel to protect the sheet metal base in the interior corners of hollow parts, even if the internal radii of the rounded edges are very small.
An aim of the invention is to apply enamel to bodies of different dimensions using the same cathode of dimensions which adapt themselves to those of the various bodies.
Another aim of the invention is to apply enamel inside bodies whose opening is smaller than their average internal cross-section.